Highly Efficient Photosensitizers with Far‐Red/Near‐Infrared Aggregation‐Induced Emission for In Vitro and In Vivo Cancer Theranostics

Abstract

Fluorescence-imaging-guided photodynamic therapy has emerged as a promising protocol for cancer theranostics. However, facile preparation of such a theranostic material for simultaneously achieving bright emission with long wavelength, high-performance reactive oxygen species (ROS) generation, and good targeting-specificity of cancer cells, is highly desirable but remains challenging. In this study, a novel type of far-red/near-infrared-emissive fluorescent molecules with aggregation-induced emission (AIE) characteristics is synthesized through a few steps reaction. These AIE luminogens (AIEgens) possess simple structures, excellent photostabilities, large Stokes shifts, bright emission, and good biocompatibilities. Meanwhile, their ROS generation is extremely efficient with up to 90.7% of ROS quantum yield, which is far superior to that of some popularly used photosensitizers. Importantly, these AIEgens are able to selectively target and ablate cancer cells over normal cells without the aid of any extra targeting ligands. Rather than using laser light, one of the presented AIEgens (MeTTPy) shows a remarkable tumor-targeting photodynamic therapeutic effect by using an ultralow-power lamp light (18 mW cm^-2 ). This study thus not only extends the applications scope of AIEgens, but also offers useful insights into designing a new generation of cancer theranostics.